Protection of agricultural crops from harmful pests, insects, moths, etc. has been an important and widely recognized problem for many years. One approach for addressing the problem is to treat the crops with insecticides, i.e., chemicals, which kill or repel pests. However, there are numerous problems with employing insecticides on agricultural crops. First, some pests such as moths go through stages in their development when they do not need nourishment and are therefore practically immune to most chemical and biological pesticide agents. Second, insecticides are sometimes harmful to animals and humans who may consume the crop materials after they are harvested. Further, in recent years the use of insecticides on crops has become heavily criticized as people have gained greater understanding about toxicology and carcinogenicity. Accordingly, alternative techniques for protecting crops from harmful pests or insects, which do not involve application of chemicals to the crops, are highly desirable and preferred.
Most ecologically safe methods of exterminating insects, including nocturnal and crepuscular moths, the most damaging pests of cotton, tobacco and some other agricultural crops, are based on the use of light traps with point sources of light. For example, see U.S. Pat. No. 2,182,230, No. 2,848,837, No. 3,319,374, No. 3,487,577; United Kingdom Patent No. 1,119,478; and French Patents No. 1,114,048 and No. 1,571,436. The methods disclosed in these patents allow an operator to catch and eliminate insect pests in a radius of not more than about 1,000 feet from the point source of light. To carry out these methods, an operator must install a number of light traps for the protection of cotton, tobacco or tea plantations. The methods require an extensive layout or network of electric wires among the plants, which interferes with or impedes agrotechnical cultivation.
The inventor on this patent has previously developed a technique for clearing insects from a field which employs light in a manner that does not require a complicated network of wires or a multitude of light sources. The inventor's prior invention is an ecologically clean method of clearing nocturnal and crepuscular moths, insect pests, from agricultural plantations. The method does not interfere with the cultivation of the plants. The method is disclosed in Russian Patent No. 2,038,783, which is attached as Exhibit A and is hereby incorporated by reference. The method involves trapping the moths in the period, preceding the evacuation of eggs, inside a scanning light beam which is about two miles long and generated by a search light on a mobile platform. The light beam first attracts the moths and moves them to an area outside the plantation, then forces them to evacuate eggs in an unfavorable environment. Consequently, the eggs perish.
However, a problem with the prior scanning beam method is that the phototropic property of the light beam diminishes with the diffusion of light. The beam has a form of a cone of approximately six feet in diameter at the source of light and about fifty feet at its end. The end of the light beam at the far end of the field which is being treated is less effective in trapping the moths.
Thus, an important object of the present invention is to provide a nonchemical method for clearing insects from an agricultural field. The method should not require a complex network of wires or a large number of light sources. The devices used in the method should not interfere or impede agrotechnical cultivation. Another important object of the invention is to provide a method which is effective for clearing insects from a field at the distal end of the light source, for example, as far as two miles from the light source.